Optical data capture devices, which include bar code readers, matrix code readers, and machine vision systems, are important tools in inspection, tracking, and other consumer and industrial applications. Generally, optical data capture device include a camera that captures an image of an object and then extracts information from the captured image.
A difficulty encountered in these devices is that of ensuring that the camera acquires an image of the object from which it can extract information. Among other things, obtaining good images means providing adequate lighting of the object, and ensuring that the object is positioned within the camera's field of view, preferably at the center of the field of view, and that the image of the object is in focus.
A final related problem is providing feedback to a user when information has been successfully extracted from a captured image. Most current devices either provide an audible tone if information is successfully extracted or have one or more light-emitting diodes (LEDs) on the chassis that light up if information is successfully extracted. Both approaches have disadvantages. If the audible tone is too loud, it quickly grows annoying to human operators, which could lead them to switch off the tone or ignore it altogether. But if the tone's volume is reduced to make it less annoying, the operator may not be able to hear the tone in a noisy environment. With LEDs on the scanner chassis, the user must look away from the object to look at the LEDs to see if they light up. This is a distraction that takes the user's attention away from keeping the object within the field of view.